Condenser microphones operate by use of a capacitor, which generally consists of two plates and a voltage between them. One of the plates of the capacitor can be formed of a lighter material, such that it acts as a diaphragm, which vibrates as it encounters sound waves. This changes the distance between the two plates and alters the capacitance. In particular, when the plates are nearer to each other, the capacitance increases inducing a charge current and when the plates are spaced farther apart, the capacitance decreases causing a discharge current. Electret condenser microphones can utilize a ferroelectric material or a permanently electrically charged or polarized material.
Condenser microphones and specifically electret condenser microphones can be used in conjunction with lavalier, lapel, earset, headset, or instrument microphones and other hands-free operation microphones. Lavalier or lapel microphones, sometimes referred to as body microphones, collar microphones, clip microphones, neck microphones or personal microphones, are often used in theatre, musical, television, public speaking, and other environments that require movement of the performer or hands free operation. These types of microphones can be provided with clips to permit attachment to various clothing, e.g., shirts, collars, ties, etc. to allow for a hands-free operation. In certain examples, the cords can be hidden underneath clothing and can be connected directly to a mixer or other recording device or can be connected to a body pack receiver worn on the user, which can transmit a signal to a mixer or other recording device.